Process for making an omicron-higher alkyl omicron-methyl methanephosphonate



United States Patent 3,138,629 PROCESS FOR MAKING AN O-HIGHER ALKYLO-METHYL METHANEPHOSPHONATE Robert G. Laughlin, Cincinnati, Ohio,assignor to The Procter & Gamble Company, Cincinnati, Ohio, acorporation of Ohio t No Drawing. Filed Jan. 19, 1961, Ser. No. 83,612

Claims. (Cl. 260-461) This invention relates to new surface activecompounds and to new processes for preparing such compounds. Moreparticularly the new compounds to which this invention relates arecertain new phosphonate and phosphate esters, which in turn are commonlyclassed as pentavalent organophosphorous esters.

A primary object of the invention is to make available new surfaceactive compounds which can be prepared from available sources and whichare especially useful in hard water because they are not precipitated bythe mineral constituents thereof and because their efficiency is notimpaired by hard Water. Other objects will become apparent in thedescription which follows.

The new compounds of this invention are of the general formula where Ris an alkyl or alkoxy radical having from 1 to about 3 carbon atoms, R"is an alkyl radical having from 1 to about 3 carbon atoms, and R is analkyl or alkenyl radical having from about 12 to about 18 carbon atoms.It will be noted that where R is an alkyl radical the compounds arephosphonate esters; whereas, where R is an alkoxy radical the compoundsare phosphate esters.

All of the compounds represented by the above general formulademonstrate surface active properties. However, it has been found thatas the chain length of R and R increases, R remaining constant, surfaceactivity decreases. Therefore it is desirable that the carbon chainsrepresented by R and R contain not more than 3 carbon atoms. Preferredcompounds are those in which R is an alkyl radical having 1 carbon atom,CH or an alkoxy radical having 1 carbon atom, CH O, and R is an alkylradical having 1 carbon atom, CH Moreover, it has been discovered thatoptimum efiicacy of these compounds as surfactants in aqueous solutionis obtained when R is a saturated alkyl radical having about 12 carbonatoms. In view of the aforementioned discoveries, this invention regardsmethyldodecyl methylphosphonate CHsO and dimethyldodecyl phosphate CHQOO Patented June 23, 1964 phate compounds will be as is ilustrated in thepreceding paragraph; that is, the appropriate nomenclature describingthose alkyl or alkenyl radicals shown in the formulae as being attacheddirectly to the phosphorus atom is Written as one word with the parentterm "phosphonate, and the appropriate nomenclature describing thosealkyl or allcenyl radicals shown as being attached to the phosphorusatom by an oxygen atom is written apart from and preceding theappropriate parent term.

Briefly and broadly, the process for preparing the new phosphonate andphosphate esters comprises the steps of: reacting a compound of thegeneral formula RIIO R!!! where R is an alkyl or alkoxy radical havingfrom 1 to about 3 carbon atoms and R" and R" are alkyl radicals havingfrom 1 to about 3 carbon atoms, with an alkylating agent of the generalformula RX, where R is an alkyl or alkenyl radical having from about 12to about 18 carbon atoms and X is a bromide, iodide or acetate radical;and separating the desired compound prepared, which compound is of thegeneral formula R'\ /O P/ RO \OR where R, R and R are as defined above,from the reac-, tion by-products. These by-products are in the main ofthe general formulae ing made to draw a balance between reactants andreaction products:

where R, R, R and R are as defined above.

With regard to the molar ratio of organophosphorus ester to alkylatingagent employed in the process of this invention such ratio is preferablyat least 1:1. A higher molar ratio can be used if desired, because thereis no criticality with respect to the top limit except for economicconsiderations.

The conditions of the general reaction comprise: heating the reactantsat a temperature within the range of from about C. to about 250 C. andsufficient to initiate the reaction; at a pressure suflicient tomaintain the reactants in a substantially liquid state; and for fromabout 10 to about 50 hours and sufficient to form the compounds of thisinvention.

The reactants employed in this invention, i.e., the particularphosphonates, phosphates and alkylating agents,

are readily obtained by various methods well known in the art. Forexample: the Michaelis-Arbuzov reaction forms phosphonates by reacting aphosphite with an alkyl halide, as described by G. M. Kosolapoff inJournal of the American Chemical Society, vol. 66, page 109 (1944);phosphates can be prepared by reacting phosphorus oxycholride and analcohol in the presence of a tertiary amine; the halide alkylatingagents can be formed by radical initiated addition of hydrogen halide(HX) to l-olefins having the appropriate long carbon chain or byreacting an alcohol having the appropriate long carbon chain withhydrogen halide (HX); and the acetate alkylating agents can be obtainedby reacting alcohols having the appropriate long carbon chain with anacetylating agent, such as acetyl chloride or acetic anhydride.

It should be recognized that regardless of whether the new surfactantdesired is to be a phosphonate ester or a phosphate ester theaforementioned bromide, iodide or acetate alkylating agents are suitablefor use in the process of the invention. However for various reasons theuse of certain of these agents is preferred. Because the halidealkylating agents provide larger product yields and do not require theutilization of an autoclave or similar device to obtain a substantialyield, their use is preferable to that of the acetate alkylating agents.Furthermore, of the suitable halide alkylating agents, alkyl bromide ispreferred because the unreacted alkyl bromide is easier to separate fromthe reaction products than is the unreacted alkyl iodide.

As mentioned hereinbefore in connection with the conditions applicableto the general reaction of the invention, the reactants are heated at atemperature within the range of from about 160 C. to about 250 C. forfrom about to about 50 hours.

In this regard it has been found that various portions of thistemperature range provide the best results depending on the type ofalkylating agent employed, roughly as follows: because of the relativelyhigh reactivity of iodide alkylating agents, they function best when thetemperature is maintained within the range of from about 160 C. to about200 C.; the acetate alkylating agents function best when the temperatureis maintained within the range of from about 220 C. to about 250 C.; andthe bromide alkylating agents function best when the temperature ismaintained within the range of from about 180 C. to about 220 C. Sincethe acetate alkylating agents employed in this invention tend tovolatilize at temperatures approaching 250 C., it is necessary that thereaction be run under a pressure sufficient to keep the reactantssubstantially in a liquid state. A preferable procedure is to conductthe reaction in an autoclave to avoid the loss of volatile components. 7

Turning next to a consideration of the preferred period of time, interms of hours, during which the reactants should be heated, it is to benoted that when the bromide alkylating agents are employed it isdesirable that the period of time during which the reactants are heatedbe within the range of from about to about 25 hours. As noted above, theiodide alkylating agents are more reactive than the other alkylatingagents used in the reaction. Therefore, when the iodide alkylatingagents are employed it is desirable for the purpose of reducingby-product formation to react the starting materials for from about 10to about hours. Moreover, it is preferable that when the acetatealkylating agents are employed the time during which the reactants areheated be within the range of from about 15 to about hours. 7

The following examples are illustrative of the invention. All materialswere initially at room temperature; and the temperatures referred to inthese examples are reaction temperatures. Also illustrated by thefollowing examples is the preferred molar ratio of the organophosphorousester reactant and the alkylating agent which is 1:1 to about'4zl.

Example I Methyldodecyl methylphosphonate was prepared as follows.Equimolar amounts (0.1 mole) of dodecyl bromide and dimethylmethylphosphonate were placed in a 3-neck flask. The flask was fittedwith a thermometer, a condenser and a nitrogen inlet. During thereaction a slight positive nitrogen pressure l-5 mm. Hg) was maintained.The flask containing the reactants was heated in an oil bath for 16hours at 185 C. and then for 3 hours at 205 C. The methyldodecylmethylphosphonate prepared was separated from the unreacted startingmaterials and from the didodecyl methylphosphonate which was formed as aby-product of the reaction by vacuum distillation. The yield ofmethyldodecyl methylphosphonate was 38% of theoretical, based on theamount of dodecyl bromide employed.

Employing the method of Harkins and Jordan as set forth in J. Am. Chem.Soc., vol. 52, p. 1751 (1930), which method utilizes a Du Nouy SurfaceTensiometer, it was established that the methyldodecyl methylphosphonateprepared above possesses surface active properties. The result of thistest is shown in tabular form below; the readings being convertible intoa dynes/cm. figure by multiplying by 1.07:

Hexadecyl bromide can be substituted for dodecyl bromide in the aboveexample to form methyl hexadecyl methylphosphonate, which ester hassurface active properties.

Example II 0.25 mole of dodecyl bromide was reacted with 0.49 mole ofdiethyl ethylphosphonate according to the process described in ExampleI, with the exception that the reactants were heated for 20 hours at 200C. The yield of the ethyldodecyl ethylphosphonate formed afterseparation by vacuum distillation from the unreacted starting materialsand from the didodecyl ethyl phosphonate which was formed as aby-product of the reaction was 58% of theoretical, based on the amountof dodecyl bromide employed. The ethyl dodecyl ethylphosphonate wasfound to have surface active properties.

Hexadecyl bromide can be substituted for dodecyl bromide in the aboveexample to form ethylhexadecyl ethylphosphonate, which ester has surfaceactive properties.

Example Ill Equimolar amounts (0.2 mole) of dodecyl iodide and dimethylmethylphosphonate were reacted according to the process described inExample I, with the exception that the reactants were heated for 1 hourat C. and then for 19 hours at C. The yield of the methyldodecylmethylphosphonate obtained after separation by vacuum distillation fromthe unreacted starting materials and from the didodecylmethylphosphonate which was formed as a by-product of the reaction was34% of theoretical, based on the amount of dodecyl iodide'used. Themethyldodecyl methylphosphonate was found to have surface activeproperties.

Hexadecyl iodide or hexadecyl bromide can be substituted for dodecyliodide in the above example to form methylhexadecyl methylphosphonate,which ester has surface active properties.

Dimethyldodecyl phosphate was prepared by reacting 0.25 mole of dodecylbromide with 0.5 mole of trimethyl phosphate according to the processdescribed in Example I, with the exception that the reactants wereheated for 4 hours at 195 C. and then for 14 hours at 215 C. The yieldof dimethyldodecyl phosphate after separation by vacuum distillationfrom the unreacted starting materials and from the methyldidodecylphosphate which was formed as a by-product of the reaction was 54% oftheoretical, based on the amount of dodecyl bromide employed.

The dimethyldodecyl phosphate obtained was then tested for surfaceactive properties by the Harkins and Jordan method described in ExampleI. The results of the test is shown in tabular form below; the readingsbeing convertible into a dynes/ cm. figure by multiplying by 1.07:

Dimethylpropyl thosphate can be substituted for trimethyl phosphate inthe above example to form an ester which has surface active properties.

Example V 0.25 mole of dodecyl bromide was heated with 0.5 mole oftriethyl phosphate for 4 hours at 205 C. and then for 6 hours at 215 C.using the process described in Example I. The yield of diethyldoceylphosphate after separation by vacuum distillation from the unreactedstarting materials and from the ethyldidodecyl phosphate which wasformed as a by-product of the reaction was 63% of theoretical, based onthe amount of dodecyl bromide employed.

Employing the Harkins and Jordan method, described in Example I, showedthe diethyldodecyl phosphate produced by this example to be a surfaceactive agent. The result of this test is shown in tabular form below;the readings being convertible into a dynes/cm. figure by multiplying by1.07:

Decease in water sruface tension Du Nouy Teusiometer caused by a ExampleVI Dirnethylhexadecyl phosphate was prepared by heating 0.2 mole ofhexadecyl iodide with 0.8 mole of trimethyl phosphate for hours at 190C., according to: the process described in Example I. The yield ofdimethylhexadecyl phosphate after separation by vacuum distillation fromthe unreacted starting materials and from the methyldihexadecylphosphate which was formed as a by-product of the reaction was 55% oftheoretical, based on the amount of hexadecyl iodide employed. Thedimethylhexadecyl phosphate was found to have surface active properties.

Dodecenyl bromide or hexadecenyl iodide can be substituted in the aboveexample to form esters which have surface active properties.

6 Example VII Equimolar amounts (0.3 mole) of dodecyl acetate anddimethyl methylphosphonate were sealed in a glass lined autoclave. Thereactants were then heated in the autoclave for 18 hours at atemperature of 250 C. The methyldodecyl methylphosphonate prepared wasseparated by vacuum distillation from the starting materials and fromthe didodecyl methylphosphonate which was formed as a by-product of thereaction. The yield of methyldodecyl methylphosphonate after separationby vacuum distillation from the unreacted starting materials and fromthe diodecyl methylphosphonate which was formed as a by-product of thereaction was 28% of theoretical, based on the amount of dodecyl acetateemployed. The methyldodecyl methylphosphonate was: found to have surfaceactive properties.

Example VIII Equimolar amounts (0.15 mole) of dodecyl acetate anddimethyl methylphosphonate were reacted according to the processdescribed in Example VII, with the exception that the reactants wereheated for 48 hours. The yield of methyldodecyl methylphosphonate formedafter separation by vacuum distillation from the unreacted startingmaterials and from the didodecyl methylphosphonate which was formed as aby-product of the reaction was 15% of theoretical, based on the amountof dodecyl acetate employed. The methyldodecyl methylphosphonate wasfound to have surface active properties.

What is claimed is: V

1. A process for preparing mono-higher alkyl phosphonate ester compoundof the general formula where R and R are each methyl and R is alkylhaving 12 carbon atoms, consisting essentially of reacting anorganophosphorous ester compound of the general formula where R and R"are each methyl, and R' is alkyl having from 1 to about 3 carbon atoms,with an alkylating agent of the general formula RX, where R is alkylhaving 12 carbon atoms, and X is bromide the molar ratio of saidorganophosphorous ester reactant to said alkylating agent being from 1:1to about 4:1, at a temperature within the range of from about 180 C. toabout 220 C. for from about 15 to about 25 hours under substantiallyatmospheric pressure said reaction being a purely thermal reaction, andthereafter, recovering the mono-higher alkyl phosphonate ester reactionproduct.

2. A process for preparing mono-higher alkyl phos phonate ester compoundof the general formula where R and R" are each methyl and R is alkylhaving 12 carbon atoms consisting essentially of reacting anorganophosphorous ester compound of the general formula i RI O RIIIwhere R and R" are each methyl, and R is alkyl having from 1 to about 3carbon atoms, with an alkylating agent of the general formula RX, whereR is alkyl having 12 carbon atoms and X is iodide the molar ratio ofsaid orgahophosphorous ester reactant to said alkylating agent beingfrom 1:1 to about 4: 1, at a temperature within the range of about 160C. to about 200 C., for from about 10 to about 20 hours undersubstantially atmospheric pressure said reaction being a purely thermalreaction, and, thereafter recovering the mono-higher alkyl phosphonateester reaction product.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Arbuzov et al.: Bull. Acad. Sci. U.S.S.R., Div. Chem. Sci.,(English Trans.), pp. 787-795, 1952.

Burger: U.S. Atomic Energy Comm. HW-44888, Janu- 15 ary 3, 1957, pp.1-25.

1. A PROCESS FOR PREPARING MONO-HIGHER ALKYL PHOSPHONATE ESTER COMPOUNDOF THE GENERAL FORMULA